No digital or analog pulse width modulation (PWM) generating device currently has the capability to vary the PWM phase offset while the PWM generating device is in operation. Existing digital PWM generating devices that are integrated with a microcontroller are designed to address technical requirements in the motor control industry.
In existing analog PWM generation devices, the phase relationship among the PWM output signals is fixed by design. Vendors produce devices for two, three or four phase outputs where the phase relationship among the outputs is evenly spread throughout the PWM cycle. A digital PWM module 1304 with a capability to offset the phase of the PWM signals is implemented in the Motorola MC68HC08SR12 and MC68HC908SR12 devices, but these devices can not vary the phase relations among the PWM outputs while the PWM generator is operational. U.S. Pat. No. 6,525,501, issued Feb. 25, 2003, describes a method for implementing multiple simultaneous duty cycle register updates.
There is, therefore, a need in the art for dynamically updateable PWM phase offset capability required for new power supply applications including format modes, phase shifting capability, multiple simultaneous PWM duty cycle register updating, and advanced analog-to-digital converter (ADC) trigger timing capabilities.